What do you mean with "last version of the game"? Are the assets not updated, or is it running older code? And is the game up to date if you launch the GameLauncher instead of the Sandbox?
If the assets are out of date in the packaged build it could be that you forgot to export to engine in the Sandbox. You can do this by opening your level in the Sandbox, and going to File→Export to Engine. Now either run the GameLauncher or package your build and the new assets should be in place.
Another thing that could've gone wrong is that the package system is packaging the wrong game dll file. It copies the dll file that is referenced to in the .cryproject file, but if you've build your .dll file to a different location (for example by switching the configuration between Debug, Profile, and Release) it might pick the wrong .dll file. Double check that your dll file is in the same location as the .cryproject file specifies to make sure it packages the right one.
Thanks @cry-miron! The problem was that i didn't export to the engine properly because of an AI navigation error, and i was clicking yes and that was canceling the export.